Cobar启动完成，监听特定端口。整个认证的流程图： NIOAcceptor类继承自Thread类，该类的对象会以线程的方式运行，进行连接的监听。NIOAcceptor启动的初始化过程如下：1 、打开一个selector，获取一个ServerSocketChannel对象，对该对象的socket绑定特定的监
Cobar启动完成，监听特定端口。整个认证的流程图：
NIOAcceptor类继承自Thread类，该类的对象会以线程的方式运行，进行连接的监听。
NIOAcceptor启动的初始化过程如下：
1 、打开一个selector，获取一个ServerSocketChannel对象，对该对象的socket绑定特定的监听端口，并设置该channel为非阻塞模式，然后想selector注册该channel，绑定感兴趣的事件位OP_ACCEPT。
public NIOAcceptor(String name, int port, FrontendConnectionFactory factory) throws IOException {
super.setName(name);
this.port = port;
this.selector = Selector.open();
this.serverChannel = ServerSocketChannel.open();
//ServerSocket使用TCP
this.serverChannel.socket().bind(new InetSocketAddress(port));
this.serverChannel.configureBlocking(false);
this.serverChannel.register(selector, SelectionKey.OP_ACCEPT);
this.factory = factory;
} public void run() {
final Selector selector = this.selector;
//线程一直循环
for (;;) {
++acceptCount;
try {
selector.select(1000L);
Set<SelectionKey> keys = selector.selectedKeys();
try {
for (SelectionKey key : keys) {
if (key.isValid() && key.isAcceptable()) {
//接受来自客户端的连接
accept();
} else {
key.cancel();
}
}
} finally {
keys.clear();
}
} catch (Throwable e) {
LOGGER.warn(getName(), e);
}
}
}private void accept() {
SocketChannel channel = null;
try {
//从服务器端获取管道,为一个新的连接返回channel
channel = serverChannel.accept();
//配置管道为非阻塞
channel.configureBlocking(false);
//前端连接工厂对管道进行配置，设置socket的收发缓冲区大小，TCP延迟等
//然后由成员变量factory的类型生产对于的类型的连接
//比如ServerConnectionFactory会返回ServerConnection实例，并对其属性进行设置
FrontendConnection c = factory.make(channel);
//设置连接属性
c.setAccepted(true);
c.setId(ID_GENERATOR.getId());
//从processors中选择一个NIOProcessor，将其和该连接绑定
NIOProcessor processor = nextProcessor();
c.setProcessor(processor);
//向读反应堆注册该连接，加入待处理队列
//select选择到感兴趣的事件后，会进行调用connection的read函数
processor.postRegister(c);
} catch (Throwable e) {
closeChannel(channel);
LOGGER.warn(getName(), e);
}
}
FrontendConnectionFactory是一个抽象类，其中的getConnection方法是抽象方法，有具体子类连接工厂来实现。FrontendConnectionFactory的make方法对channel中的socket进行属性设置（接收和发送的缓冲区大小、延时、KeepAlive等），然后调用具体调用具体子类（ServerConnectionFactory）的getConnection来返回一个ServerConnection，返回后会在进行设置一下该ServerConnection的包头大小、最大包大小、设置连接的发送缓冲区队列、超时时间、字符编码，到此，工厂完成了新建连接的工作，返回一个连接的对象。返回后将该连接分配给一个processor，该processor会将该连接保存，processor也会对连接进行定期检查。
5、 processor还会向自己的reactorR进行注册该连接，加入reactorR的处理队列，并唤醒阻塞的select()方法。
反应堆中Reactor的R线程运行代码：
public void run() {
final Selector selector = this.selector;
for (;;) {
++reactCount;
try {
int res = selector.select();
LOGGER.debug(reactCount + ">>NIOReactor接受连接数:" + res);
register(selector);
Set<SelectionKey> keys = selector.selectedKeys();
try {
for (SelectionKey key : keys) {
Object att = key.attachment();
if (att != null && key.isValid()) {
int readyOps = key.readyOps();
if ((readyOps & SelectionKey.OP_READ) != 0) {
LOGGER.debug("select读事件");
read((NIOConnection) att);
} else if ((readyOps & SelectionKey.OP_WRITE) != 0) {
LOGGER.debug("select写事件");
write((NIOConnection) att);
} else {
key.cancel();
}
} else {
key.cancel();
}
}
} finally {
keys.clear();
}
} catch (Throwable e) {
LOGGER.warn(name, e);
}
}
}?channel.register(selector, SelectionKey.OP_READ, this);注意最后一个this指针参数，表示将该连接作为附件，注册到selector，当有感兴趣的时间发生时，函数selector.selectedKeys()返回的SelectionKey集合中的对象中使用key.attachment()即可获取到上面注册时绑定的connection对象指针附件。目的就是为了通过该附件对象调用该连接类中定义的read函数来完成功能。如下所示：
private void read(NIOConnection c) {
try {
c.read();
} catch (Throwable e) {
c.error(ErrorCode.ERR_READ, e);
}
} public void handle(final byte[] data) {
// 从线程池获取一个线程,异步处理前端数据
// 从processor中的线程池中获取一个可以执行的线程,执行Runnable任务
processor.getHandler().execute(new Runnable() {
@Override
public void run() {
try {
//调用具体NIOHandler子类的handle函数
handler.handle(data);
} catch (Throwable t) {
error(ErrorCode.ERR_HANDLE_DATA, t);
}
}
});
} public FrontendConnection(SocketChannel channel) {
super(channel);
.....................
//前端认证处理器
this.handler = new FrontendAuthenticator(this);
}
登录认证报文的报文数据部分格式如下：
10、 FrontendAuthenticator类对上面的数据包的具体处理如下：
public void handle(byte[] data) {
// check quit packet
if (data.length == QuitPacket.QUIT.length && data[4] == MySQLPacket.COM_QUIT) {
source.close();
return;
}
//新建认证包对象
AuthPacket auth = new AuthPacket();
//读取认证包到对象
auth.read(data);
// check user
if (!checkUser(auth.user, source.getHost())) {
failure(ErrorCode.ER_ACCESS_DENIED_ERROR, "Access denied for user '" + auth.user + "'");
return;
}
// check password
if (!checkPassword(auth.password, auth.user)) {
failure(ErrorCode.ER_ACCESS_DENIED_ERROR, "Access denied for user '" + auth.user + "'");
return;
}
// check schema
switch (checkSchema(auth.database, auth.user)) {
case ErrorCode.ER_BAD_DB_ERROR:
failure(ErrorCode.ER_BAD_DB_ERROR, "Unknown database '" + auth.database + "'");
break;
case ErrorCode.ER_DBACCESS_DENIED_ERROR:
String s = "Access denied for user '" + auth.user + "' to database '" + auth.database + "'";
failure(ErrorCode.ER_DBACCESS_DENIED_ERROR, s);
break;
default:
//认证成功,向客户端发送认证结果消息
success(auth);
}
} protected void success(AuthPacket auth) {
//认证通过,设置连接属性:已认证\用户\数据库\处理器
source.setAuthenticated(true);
source.setUser(auth.user);
source.setSchema(auth.database);
source.setCharsetIndex(auth.charsetIndex);
//设置该连接的连接处理器为前端命令处理器
source.setHandler(new FrontendCommandHandler(source));
.......
ByteBuffer buffer = source.allocate();
source.write(source.writeToBuffer(AUTH_OK, buffer));
}16:59:19,388 INFO =============================================== 16:59:19,389 INFO Cobar is ready to startup ... 16:59:19,389 INFO Startup processors ... 16:59:19,455 INFO Startup connector ... 16:59:19,460 INFO Initialize dataNodes ... 16:59:19,506 INFO dnTest1:0 init success 16:59:19,514 INFO dnTest3:0 init success 16:59:19,517 INFO dnTest2:0 init success 16:59:19,527 INFO CobarServer is started and listening on 8066 16:59:19,527 INFO =============================================== 16:59:23,459 DEBUG 1>>NIOReactor接受连接数:0 16:59:23,464 DEBUG 2>>NIOReactor接受连接数:1 16:59:23,465 DEBUG select读事件 16:59:23,465 INFO com.alibaba.cobar.net.handler.FrontendAuthenticator接收的请求长度:62 58 0 0 1 5 166 15 0 0 0 0 1 33 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 114 111 111 116 0 20 169 171 247 102 133 96 158 224 121 22 226 229 88 244 119 238 185 61 124 219 16:59:23,468 INFO [thread=Processor1-H0,class=ServerConnection,host=192.168.137.8,port=46101,schema=null]'root' login success
yan@yan-Z400:~$ mysql -uroot -p** -P8066 -h192.168.137.8 Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 1 Server version: 5.1.48-cobar-1.2.7 Cobar Server (ALIBABA) Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved. Oracle is a registered trademark of Oracle Corporation and/or its affiliates. Other names may be trademarks of their respective owners. Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. mysql>
本文出自：http://blog.geekcome.com, 原文地址：http://blog.geekcome.com/%e5%88%86%e5%b8%83%e5%bc%8f%e6%95%b0%e6%8d%ae%e5%ba%93%e4%b8%ad%e9%97%b4%e4%bb%b6-2-cobar%e4%b8%8e%e5%ae%a2%e6%88%b7%e7%ab%af%e7%9a%84%e6%8f%a1%e6%89%8b%e8%ae%a4%e8%af%81, 感谢原作者分享。
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